Process for reacting propane with olefins



Patented Dec. 18, 1945 PROCESS FOR RgACTING PROPANE WITH LEFINS Frederick E. Frey, Bartleeville, Okla., assignor to Phillips Petroleum Company, a corporation of Delaware Application December 13, 1943, Serial No. 514,155 14 Claims. ((31. 2604834) This invention relates to a process of catalyti- Y cally reacting propane with olefins or other alkylating agents. Usually the olefin or alkylating agent has a relatively low number of carbon atoms, ethylene being the preferred olefin.

The principal object of the present invention is to provide a process of reacting propane with olefins or other alkylating agents. Another object is to provide a process of reacting propane with ethylene. Another object is to convert propane and ethylene to butanes and heavier hydrocarbons.

This application is a continuation-in-part of my copending application Serial Number 467,954

. filed December 5, 1942, which discloses'a catalytic process for alkylating comparatively inert para'flin hydrocarbons, such as n-butane, with olefins. The accompanying drawing portrays diagrammatically one arrangement of equipment suitable for carrying out the present invention.

I hav now discovered that propane reacts with alkylating agents, especially aliphatic olefins, preferably ethylene, in the presence of hydrofluoric acid containing a minor proportion of boron fluoride, to produce butanes and heavier paraffin hydrocarbons.

Propane and an olefin, preferably ethylene, together with hydrofluoric acid containing 2 to 7 weight per cent of BFa, are intimately contacted in a reactor by mechanical agitation, as by means of stirrers or jets. After a suitable contact time, the mixture in the reactor is withdrawn to a settler, in which the acid and hydrocarbon phases separate. The acid phase is withdrawn from the bottom and returned to the reactor. A portion of the acid phase maybe passed to a regenerator for the recovery of HF and BF: from the spent cata lyst. The hydrocarbon phase passes from the top of the settler to an azeotrope column which removes dissolved. HF and BF: from the hydrocarbon phase and returns them, together with some light hydrocarbon, to th reactor. A hydrocarbon stream free from HF and BF: passes from the bottom of the azeotrope column to the fractionators, in which it is separated into the fractions: ethane and lighter, propane, other desired fractions. and residue. The propane is recycled to the reactor, and the heavier fractions are withdrawn as products of the process.

peratures in the range 100 to 250 F., contact times of l to 100 minutes, and boron fluoride contents of 2 to '1 weight per cent of the catalyst are satisfactory.

The pressure in the reactor may range from about 200 up to about 1000 p. s. i. or higher, depending upon the temperature and the particular mixture in the reactor. The pressure preierably should be suiiicient to maintain the reaction mixture in. the liquid phase.

The propane entering the reactor should be in suiiicient molecular excess over the olefin that side reactions involving the olefins are minimized.

Usually the mol ratio of propane'to olefin in the reactor feed should be in the range of 2:1 to 10:1, or more. This mol ratio is maintained at such a, figure and other conditions are such that in the preierred practice no olefin, or ethylene, appears in the reaction efliuent.

A small amount of water, ranging from a trace to not more than the molecular equivalent of the boron fluoride in the catalyst, preierably should be present in the reactor, as it suppresses formation oran insoluble, heavy sludge. A convenient means of introducing about the optimum quantity or water is to saturate with water at least part of the hydrocarbon stream entering the reactor. The amount or water is preierably at least 0.1 per cent by weight of the catalyst.

Although all the reactions occurring in this process are not fully understood, it is beheved that among these reactions'is that of alkylation. However, the conditions necessary to induce alkylation of propane are so severe that the primary alkylate appears to undergo subsequent or secondary reactions producing butanes' and heavier paraflins. It is probable that a more or less stationary state similar to thermodynamic equilibrium is approached among the various components of the product. It is advantageous in some cases to introduce as a modifier an'aromatic hydrocarbon or a"cycloparaifin in a minor proportion, such as up to about 10 weight per cent of the propane, or hydrogen in amount such as to have a partial pressure of from up to 200 p. s. i., into the reactor in order to suppress disproportionation of the primary alkylate into homologs of higher and lower molecular weight. The process may be carried out in either a batchwise or continuous manner, the latter being ordinarily preferred in com-. mercial operation. The design and arrangement of equipment for continuous operation is well within the skill of the art and forms per se no part of the present invention.

It is noteworthy that the reaction eiliuent contains no or only insignificant amounts of'oieflns or other unsaturated materials.

Example A 365-cc. reactor equipped with a stirrer revolving at 1750 R. P. M. inside stationaryblades was charged with water. propane,.ethylene,-hydrogen fluoride, and boron fluoride in the order given. The reactor was suspended in a heated oil bath to maintain a constant temperature. After the desired reaction time, the contents oi the reactor were withdrawn into a cooled receiver, the acid hase was allowed to separate, and a sample of. the hydrocarbon phase was obtained forv examination. Data pertaining to the run are as follows:

Hydrocarbon charge composition, weight per cent:

Propane Substantially equimolecular amounts oi propane and ethylene reacted, yielding an almost equivalent amount or butanes and heavier paraflins and only a relatively small amount of a lighthydrocarbon fraction (ethane).

In the drawing a feed of propane and alkylating agent, usually a lower aliphatic olefln (by which I mean an olefln having from 2 to 5 carbon atoms) and most preferably ethylene enters reactor 2 via line I while catalyst enters via line 3. The reaction eiiiuent passes via line to separator where the two layers are allowed to form and are separately withdrawn, the acid layer via line 6 whence it is split into two portions, one being passed to regeneration and the other being recycled. The hydrocarbon layer passes via line I to fractional distillation column 8 whence the overhead is recycled via line 0 while the kettle product passes via line II to a fractional system indicated by H and from which C: hydrocarbons and lighter are vented via line l2, a propane fraction is recycled-via line l3, and one or more fractions of butanes and heavier parailins are removed at a. lower point or points, as indicated by a fraction of C4 to Ca paraflins taken on via line II. A residue of maassume but only as limited by the terms or the spirit of the appended claims.\

Many advantages of the present invention will be apparent to those skilled in the art. Among them is that a relatively cheap material now 7 largely wasted or burned as fuel, namely propane, is-converted to valuable hydrocarbons,

pane with an alkylating agent in the presence of a catalyst consisting of hydrofluoric acid containing a'minor proportion of boron fluoride.

2. The process which comprises reacting propane with a lower aliphatic olefin in the presence of a catalyst consisting of hydrofluoric acid containing a minor proportion of boron fluoride. 3. The process which comprises reacting propane with ethylene in the presence of a catalyst consisting of hydrofluoric acid containing a minor proportion of boron fluoride.

4. The process which comprises reacting propane with ethylene in the presence of a catalyst consisting of hydrofluoric acid containing from 2 to 7 weight per cent of boron fluoride.

5. The process which comprises reacting prcpane with ethylene in the presence of a catalyst consisting of hydrofluoric acid containing from 2 to 7 per cent of boron fluoride, and maintaining a moi ratio of propane to ethylene in the reaction zone of from 2:1 to 10:1.

6. The process which comprises reacting propane with an alkylating agent in the presence 02 a catalyst. consisting of hydrofluoric acid and boron fluoride at a temperature ranging from 100 to 250' F. and under a pressure ranging from 200 to 1000 pounds per square inch and such as to maintain the reaction mixture in liquid phase.

7. The process which comprises reacting propane with ethylene in the presence of a catalyst consisting of hydrofluoric acid and boron fluoride at a temperature ranging from 100 to 250 F., under pressure such as to maintain the reaction mixture in the liquid phase and for a contact time of 1 to 100 minutes.

8. The process which comprises reacting propane with ethylene in the presence of a catalyst consisting of hydrofluoric acid and boron fluoride, the mol ratio of propane to ethylene being at least 2:1 and all of the ethylene being consumed in the reaction.

9. The process which comprises reacting propane with ethylene in the presence of a catalyst consisting of hydrogen fluoride, boron fluoride in amount equal to from 2 to 7 weight per cent of the catalyst and water in amount ranging from in'amount equal to from 2 to 7 weight per cent of terials higher-boiling than the motor fuel or avi-' ation range is taken on via line It.

It will be understood that the invention is not to be taken as limited by the foregoing speciflc boron fluoride.

the catalyst and water in amount ranging from 0.1 weight per cent of the catalyst up to that amount whichis molecularly equivalent to the 11. The process which comprises reacting propane with ethylene in the presence of a catalyst consisting of hydrofluoric acid containing from details which are by way of illustration only is 2 to 7 w sht per cent of boron fluoride and a amount oi water ranging not il iqemm the molecular from a trace to equivalent of said h w 1' ride, maintaining a moi ratiojot proto ethylene in thereaction zone of from 2:1 to 10:1. carrying out said reaction at a tem perature ranging {ram 100 to 250 F., at a pressure 'suilicient to maintain the reaction mixture intho' iiquid phase and for a contact time of 1mm l to 100 minutes, withdrawing the reaction mixture from thereaction zone and separating same into an-acid phase and a hydrocarbon phase,

withdrawing said hydrocarbon phaseand fractionaliy distilling same to remove overhead the dissolved hydrogen fluoride and boron fluoride, recycling the hydrogen fluoride and boron iluoride so-reccvercd to the reaction step, iractionaily distillins the hydrocarbon residue from middletilling step and tree from hydrogen fluoride and boron fluoride to separate same into at least one fraction of ethane and lighter, a traction of propane, and at'least one traction containing butane and heavier paramnsas products 01 the process,

1 and recycling said propane fraction to the reaction step.

i2. The process which comprises reacting propane with ethylene by means of a catalyst consistingpi hydrofluoric acid and boron fluoride in the presence of a cyclic hydrocarbon selected tram-the group consisting of aromatic hydrocarbone and cycloparaflinsiin amount ranging up to 10 weight er cent of the propane, said cyclic a,so1,14a

o penta-nes from said hydrocarbon suppressing disproportionation ot the primary alkylate produced by alkylation of the propane by the ethylene.

13. The process which comprises reacting pro- I consisting oi propane and ethylene in a moi ratio or approximately 7.4 to 1, intimately contacting said charge with a catalyst consisting of hydrogen fluoride containing about 3 .8 weight per cent of boron trifluoride and about 0.1 weight per cent oi water, the volume ratio of hydrocarbon to catalyst being approximately 0.6, maintaining the mixture at a pressure or about 535 pounds per square inch and a temperature or about 169? F. for a reaction time or about 90 minutes, withdrawing the resulting reaction mixture and allowing same to separate into an acid phase and a hydrocarbon phase, and recovering butanes and hydrocarbon phase.

FREDERICK E. FREY. 

